I am going through the same thing and it is the most difficult thing that I could imagine. Slowly I am realizing that I need to see the positive in the situation's rather than indulge over the loss. It is true, it is a waste of energy to try and control things we know we have no control over. I try and see it as at least my child is wanted and loved by both parents, as unfair as it may seem in our eyes, she has people who want her and want to shower her with love. As a mother, you typically know your child on a different level, especially if you were their primary caretaker. Although there will be affects from separation, you have to ease it by keeping in constant contact with them and always make sure they know it will be okay. If they see you distressed, they will mirror your emotions. So if they see that everything is okay, the transitions and situation will be much easier for them. When I am with my daughter, I always ensure to be happy to show her things will are okay. You have to stay strong and keep pushing forward for not only yourself, but for your children. Even if they are not with you at the moment, they will always need you. Stay strong and please feel free to message me if you need support from someone who is in your shoes.